No Crank, No Lights, No Click, Battery Not Dead?

So I've read that MAD article multiple times. It's good info no doubt, and I'm thinking since I'm chasing my tail upstream of the bulkhead connector and underneath the dash, it's time to start looking hard at those issues. To answer your question, yes, between my red ammeter wire and the fusible link there is some sort of long, cylindrical plastic connector that I really can't seem to make any sense of. How do you detach it or even possibly remove it from the system if it's big trouble?

And from that article....it talks of bypassing the ammeter. Is it possible to detach the ammeter and do these modifications without removing the entire dash cluster? I'm a real novice when it comes to electrical (I know how to solder wires together and I have a multimeter to check for voltage), so a little more info on the topic would be great. I'll be getting some pictures of my bulkhead connectors and go from there. How would I know if my ammeter, fusible link, or even welded splice has failed? Seeing corrosion is one thing, but how do I test/check for failure?